Adjustable lamp



FIG. 1 is a front, right side perspective view of an adjustable lamp showing my new design;

FIG. 2 is a rear, left side perspective view thereof;

FIG. 3 is a right side elevational view thereof, the left side being a mirror image;

FIG. 4 is a top plan view thereof of an enlarged scale; and,

FIG. 5 is a front elevational view thereof. 

The ornamental design for an adjustable lamp, as shown and described. 